Revisiting TESLA in the quantum random oracle model
Selected history of Fiat-Shamir— style signatures from LWE or SIS Lyubashevsky 2012 Sigs via Fiat-Shamir Bai-Galbraith BLISS 2013 Short sigs Optimized DBGGOPSS 2014 Improvements, fast implementation TESLA 2015 Tight security reduction, fast implementation ring-TESLA Now with rings, fast implementation 2016 TESLA# Improvements, fast implementation
Selected history of Fiat-Shamir— style signatures from LWE or SIS Lyubashevsky 2012 Sigs via Fiat-Shamir Bai-Galbraith BLISS 2013 Short sigs Optimized DBGGOPSS 2014 Improvements, fast implementation TESLA This talk 2015 Tight security reduction, fast implementation ring-TESLA Now with rings, fast implementation 2016 TESLA# Improvements, fast implementation
Preamble
Given a forger... Sign Forger
...construct a P-solver Forger
Parameter choice should account for the security reduction
Tightness
The quantum random oracle model (QROM) Hash
When does ROM imply QROM? Boneh, Dagdelen, Fischlin, Lehmann, Schaffner, Zhandry
Prior work on TESLA Lyubashevsky Sigs via Fiat-Shamir Bai-Galbraith BLISS Short sigs Optimized Reduction from LWE, SIS. DBGGOPSS Proof uses Forking Lemma. Improvements, fast implementation Non-tight, re-programming. ROM but not QROM. TESLA Tight security reduction, fast implementation ring-TESLA Reduction from LWE only. Now with rings, fast implementation Tight reduction in ROM. QROM via chameleon TESLA# hash functions. Improvements, fast implementation
Our contributions (theoretical)
Our contributions (practical)
Summary of related work Katz, Wang Abdalla, Fouque, Lyubashevsky, Tibouchi Gentry, Peikert, Vaikuntanathan Boyen, Li
“Lattice-based” crypto
“Lattice-based” crypto
Learning with Errors (LWE) (matrix version)
TESLA key generation Pk: LWE yes-instance Sk: witness
TESLA sign Zero-knowledge proof (S,E) + Fiat-Shamir
TESLA sign: terminology
TESLA verify
Security theorem for TESLA
Security theorem for TESLA Tightness: Scaling factor 1.
Proof overview Sign Hash Forger
Simulator Sign Hash classical quantum Simulator classical quantum
Forger forges, even with a simulator Simulator Forger
Forger + Simulator = LWE solver Simulator Forger
Forger + Simulator = LWE solver
Yes-instances: Signature simulator
Yes-instances: Signature simulator Re-program a quantum oracle!
Re-programming in TESLA
No-instances: Good hash inputs
Search through unstructured space
Good hash inputs are rare
Parameter sets
Parameter sets
Software
Global A matrix?
Proof approach Abdalla, Fouque, Lyubashevsky, Tibouchi
Other tightly-secure LWE or SIS signatures (move to the end?)
Comparison: LWE/SIS schemes
Comparison: hash-based schemes
Recommend
More recommend